The doctrine of informed consent has become a legal and ethical standard in
psychiatry today. However, ethical problems arise if patients lose the cap
acity to give informed consent due to their psychiatric disorders. Particul
arly in the field of psychiatry, the assessment of competence of informed c
onsent to medical treatment and participation in clinical trials is a contr
oversial issue. New empirical data suggest that a high percentage of psychi
atric patients are incompetent according to defined standards for assessing
their capacity to make treatment decisions. Assessing competence according
to a sliding scale integrates the ethical principles of autonomy and benef
icence and provides help in assessing competence in clinical practice.